Grinding mill



March 18, 1952 R. ZUCKERT 2,589,917

GRINDING MILL Filed Nov. 8, 1948 2 swam-swam 1 MVP/Jfif Rlcuaao Z UCKERTMarch 18, 1952 R. ZUCKERT 2,589,917

/ GRINDING MILL Filed NOV. 8, 1948 v 2 SHEETSSHEET 2 lm mfor Rmymao ZUCKERT Patented Mar. 18, 1952 GRINDING MILL Richard Ziickert, Chard,England, assignor of one-half to L. 6 C. Hardtmuth, Inc., Blooms: bury,N. J., a corporation of New Jersey Application November 8, 19 i8, Serial No. 5 8, 9 7-3 In Great Britain November 2?, 194? 11 Claims.

This invention relates to grinding mills, especially, though notrestrictively, to mills for grindn raphite r se in t e nufa ure Ofpencils.

Various forms of wet grinding mill are known for this purpose; forexample in one form a grinding stone is superposed on, and rotatedecccntrically in relation to, a second grinding stone which is freetorotateabout its own axis as a result of the friction between thecontiguous surfaces of the two stones, the mixture of water withgraphiteto be ground being fed axially through the upper stone and passingradially outwards between said contiguous surfaces. The output of thismill is small.

In another form, a'high speed mill, the grindingstones are coaxial,their contiguous surfaces are formed with corresponding grooves andridges sothat in cross-section the grinding surface o f each stone'is ofzig-zag configuration, one stone being fixed and the other rotated andthe mixture of Water with graphite being fed in axially through therotary stone.

In still another mill a plurality of grinding blocks are urged radiallyagainst the periphery of ,a-rotary grindstone, the graphite being fed tothe contiguous surfaces of the blocks and stone through passagesformedin thevblocks. In yet another arrangement ah-rotary, grinding stone 1Ste m d w n inte na f ungon c l rin i surface and is fitted on -to acorrespondingly shaped fixed grinding stone, the mixture .of water .withgraphite, beingfed axially through the rotary stone.

According to the present invention a grinding mill comprisesv a bodypresenting an inner peripheral grinding surface, a carrier arranged to.b rot ted with n the bo y a d a leas one grinding block disposed onsaidcarrier so as to bes i eble rad ally wit res e thereto and ear againstthe innepperipheml lihdingsurface of the .body under the influence ofcentrifugal force, thejbody being arranged for the introductionthereinto of the material to be ground and for the egress of the groundmaterial.

tis d si ab e theta plura i y of. gri din blocks-should be slidablymountedon the carrier which ay e xial y arra ed with res to the ably, isarranged eccentrically so that material lying in the spaces betweenadjacent blocks is subjected to pressure as it approaches the exit fromthe body.

The invention is illustrated bythe accompanying drawings in which:

Figure 1 is a partly sectional side elevation of one form of grindingmill,. the section being taken on the line I I, Figure .2;

Figure 2 is anend elevation thereof, as seen from the left, Figure 1,with the end plate .removed; V

Figures 3 and Aaresectional .end views onthe lines III-III- and IV?IV,respectively, Figure l; and V Figures 5 and-6 are diagrammatic viewsof.two arrangements for carrying flout the grinding of,

e.. g. graphite for use in the manufacture of ing-space lattheleft-handend of the-body a,

Figural). Thediaphragm g is 'formedlwith an inlet passage 7' andanoutlet passageJcAF-igure 3)- communicating vwith the chambers (e andf, respectively.

Within the body a, at the side of the. diaphragm g remote from thechambers .ea'nd ,r a solid cylindrical carrier m (Figures 1 and 2 .ismcunted on the projecting end of .an v eccentric shaft n. carried in abearing oKFigure 14),,the diameter of the carrier-m and theeccentricityof the shaft nbein'g such that the periphery of the carriermand the inner periphery of the body a are tangential at the top of thelatter. A'pla'te napplied to theend of the body a closes, in

saidbody, the grinding space, between said plate -,With the grindingspace has "an fiijgu v clay, siliceous stone or the like to present agrinding surface and the carrier m is formed with recesses r to receivegrinding blocks s of similar material. The operative face of each blockmay be of the same curvature as the inner peripheral surface of thegrinding inset q (i. e. of the same radius as the inner peripheral wallof the body a) and, preferably, the leading end of said operative faceis of smaller radius, as indicated at t, Figure 2, for a purpose whichwill appear hereinafter.

As shown in Figure 3, the inlet passage 7' to the grinding space beginsat about 20 (in the direction of rotation of the body m) from theposition where the periphery of the body m and the inner periphery ofthe body a are tangential to one another and has an angular extent ofabout 120 and the outlet passage extends for about 20 up to saidposition.

For use the inlet 0 is connected with a source of supply (not shown inFigures 1 to 4) of a mixture of water and graphite and the shaft n isrotated by means of a belt pulley u mounted thereon and driven from aprime mover, not shown. Centrifugal force acting on the blocks s as aresult of the rotation of the carrier m causes said blocks to moveradially outwards and bear against the inner peripheral face of the bodya, and, on account of the eccentric movement of the carrier m within thebody a the device acts as a pump and the arrangement is such that someof the graphite drawn through the inlet 0 and passage 7 into a space 1:between two adjacent grinding blocks s passes,,and is ground, be-

tween the operative face of the trailing block s and the innerperipheral surface of the inset q, passes to the succeeding space and isground by the succeeding block s, and so on, the graphite being carriedround gradually as the carrier m is rotated and being compressed as thevolume of the spaces '0 is reduced, the pressure thus created serving toexpel ground graphite through the outlet passages k and d. The entranceof the graphite to the operative face of a block s being facilitated bythe space at t.

It has been stated above that the operative face of each block s may beof the same curvature as the inner peripheral surface of the body a.This indicates that in general there will be adequate surface contactbetween those two parts during the revolution of the body, but, as thepressure on the liquid increases during the second half of a revolutionof the eccentric body it is desirable that the surface contact should besuperior during said second half revolution, for whichpurpose thecurvature of the operative face of each block should approximate asnearly as possible that of the inner peripheral wall of the body whenthe block is at about 45 in rear of the position at which said surfaceand wall ar tangential.

In order to ensure thorough grinding of the graphite repetition of theoperation is desirable, for which purpose, shown by way of example inFigure 5, the inlet 0 and outlet d may be connected with a storagevessel w, in which the liquid mixture may be stirred to preventprecipitation and from which it may be drawn and passed again throughthe mill. Alternatively, as shown in Figure 6, a plurality of mills maybe connected in series so that the output from one mill passes direct tothe inlet of the next mill of the series and so on.

been carried round in a space 1) and thus escaped being ground) will, intime, be subjected to the desired grinding operation.

If desired the body a and/or the vessel w may be water jacketed but itwill usually be found sufficient to cool the liquid as it passes toand/or from the vessel to or when a series of mills is employed as itpasses from one mill to the next.

In some cases springs may be provided to ensure contact of the operativefaces of the blocks 1' with'the inner peripheral surface of the body aso as to ensure that pumping action will commence as soon as the carrierm is rotated.

Although the inlet and outlet passages j and it provide for the entranceof the liquid into the grinding space, and its exit therefrom, in adirection parallel with the axis of rotation of the carrier m, suchentrance and exit may be arranged in the radial direction, but theformer is preferable as it enables the maximum grinding surface to bepresented in a mill of any given size.

If desired, pressure... (positive and negative) means may be providedfor facilitating the introduction of the material into, and its exitfrom,

the body a, such pressure means may be 00- ordinated with the rotationof the carrier so that impulses occur when spaces between adjacentblocks are opposite the entrance and exit passages.

A grinding mill constructed in accordance with this invention is adaptedfor operation at high speed, the graphite is not subjected to anythingbut simple grinding action, i. e. it is never subjected to beating,stamping or other impact as in some of the known mills and yet theimproved mill has a greater output than the known forms of mere grindingmills.

I claim:

1. A grinding mill comprising a cylindrical body presenting an innerperipheral abrasive surface, a carrier mounted to rotate within saidbody about an axis eccentric to the axis of the body. at least oneabrasive block mounted in said carrier and slidable radially withrespect thereto so as to bear against the grinding surface under theinfluence of centrifugal force, and an inlet and outlet into thegrinding space of the body located on opposite sides of a radial planethrough the point of closest approach of the carrier to the body.

2. A grinding mill as claimed in claim 1 having a plurality of radiallyslidable blocks.

3. A grinding mill as claimed in claim 2, in which the inlet to thegrinding space extends from about 20, in the direction of rotation ofthe body, from such point to about fromsaid point and an outletextending through about 20 up to said point.

4. A grinding mill as claimed in claim 3, wherein the operative face ofeach abrasive block has the same curvature as the inner peripheralsurface of the body. 1

5. A grinding mill as claimed in claim 4, wherein the leading end of theoperative surface of each abrasive block is of reduced radius.

6. A grinding mill as claimed in claim 1, in which the inlet to thegrinding space extends from about 20, in the direction of rotation ofthe body, from such point to about 140 from said point and an outletextending through about 20 up to said point. r

7. A grinding mill as claimed in claim 6, wherein the operative face ofeach abrasive block has the same curvature as the inner peripheralsurface of the body.

8. A grinding mill as claimed in claim 7, wherein the leading end of theoperative surface of each abrasive block is of reduced radius.

9. A grinding mill as claimed in claim 1, wherein the operative face ofthe abrasive block has the same curvature as the inner peripheralsurface of the body.

10. A grinding mill as claimed in claim 1, wherein the leading end ofthe operative surface of the abrasive block is of reduced radius.

11. A grinding mill as claimed in claim 1 in which said surface andblock are of a material selected from the group consisting of hardporcelain, fire clay and siliceous stone.

RICHARD ziicKER'r.

REFERENCES CITED Number Number 6 UNITED STATES PATENTS Name Date LucopFeb. 15, 1876 Corcoran Aug. 5, 1884 Hilton July 28, 1885 Pamphilon Jan.23, 1894 Suttie Aug. 13, 1901 Wallace Feb. 11, 1902 Knapp Sept. 19, 1905Besser Jan. 4, 1908 Arpin Oct. 20, 1928 Estey Feb. 22, 1949 LivermoreMar. 7, 1950 FOREIGN PATENTS Country .Date Sweden Apr. 17, 1934 Thefollowing references are of record in the 20 file of this patent:

